The invention concerns novel compounds and pharmaceutically acceptable salts thereof, their use, either alone or in combination with other therapeutic agents, in the treatment or prophylaxis of HIV infection, and to pharmaceutical compositions comprising the compounds.
The disease known as acquired immune deficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV), particularly the strain known as HIV-1. In order for HIV to be replicated by a host cell, the information of the viral genome must be integrated into the host cell""s DNA. However, HIV is a retrovirus, meaning that its genetic information is in the form of RNA. The HIV replication cycle therefore requires a step of transcription of the viral genome (RNA) into DNA, which is the reverse of the normal chain of events. An enzyme that has been aptly dubbed reverse transcriptase (RT) accomplishes the transcription of the viral RNA into DNA. The HIV virion includes a copy of RT along with the viral RNA.
Reverse transcriptase has three known enzymatic functions; it acts as an RNA-dependent DNA polymerase, as a ribonuclease, and as a DNA-dependent DNA polymerase. Acting as an RNA-dependent DNA polymerase, RT transcribes a single-stranded DNA copy of the viral RNA. Acting as a ribonuclease, RT destroys the original viral RNA, and frees the DNA just produced from the original RNA. Finally, acting as a DNA-dependent DNA polymerase, RT makes a second, complementary DNA strand, using the first DNA strand as a template. The two strands form double-stranded DNA, which is integrated into the host cell""s genome by another enzyme called integrase.
Compounds that inhibit the enzymatic functions of HIV-1 reverse transcriptase will inhibit replication of HIV-1 in infected cells. Such compounds are useful in the prevention or treatment of HIV-1 infection in human subjects, as demonstrated by known RT inhibitors such as 3xe2x80x2-azido-3xe2x80x2-deoxythymidine (AZT), 2xe2x80x2,3xe2x80x2-dideoxyinosine (ddI), 2xe2x80x2,3xe2x80x2-dideoxycytidine (ddC), d4T, 3TC, Nevirapine, Delavirdine, Efavirenz and Abacavir, the main drugs thus far approved for use in the treatment of AIDS.
As with any antiviral therapy, use of RT inhibitors in the treatment of AIDS eventually leads to a virus that is less sensitive to the given drug. Resistance (reduced sensitivity) to these drugs is the result of mutations that occur in the reverse transcriptase segment of the pol gene. Several mutant strains of HIV have been characterized, and resistance to known therapeutic agents is due to mutations in the RT gene. Some of the most commonly observed mutants in the clinic are: the Y181C mutant, in which a tyrosine (Y) at codon 181 has been mutated to a cysteine (C) residue and K103N where the lysine (K) at position 103 has been replaced by asparagine (N). Other mutants, which emerge with increasing frequency during treatment with known antivirals, include the single mutants V106A, G190A, Y188C, and P236L; and the double mutants K103N/Y181C, K103N/P225H, K103N/V108I, and K103N/L100I.
Continued use of antiviral compounds to prevent HIV infection will undoubtedly cause an increased emergence of new resistant strains of HIV. There is therefore an ongoing need for new inhibitors of RT, with different patterns of effectiveness against the various mutants.
Compounds having tricyclic structures, which are inhibitors of HIV-1, are described in U.S. Pat. No. 5,366,972. Other inhibitors of HIV-1 reverse transcriptase are described in Hargrave et al., J. Med. Chem., 34, 2231 (1991).
U.S. Pat. No. 5,705,499 proposes 8-arylalkyl- and 8-arylheteroalkyl-5,11-dihydro-6H-dipyrido[3,2-B:2xe2x80x2,3xe2x80x2-E][1,4]diazepines as inhibitors of RT. The exemplified compounds are shown to have some activity against wild type and mutant HIV-1 RT, particularlyY181C and other single mutants such as K103N albeit less effectively.
WO 01/96338A1 and U.S. Pat. No. 6,420,359 disclose diazepine structures having quinoline and quinoline-N-oxide substituents as inhibitors of RT. The exemplified compounds have activity against HIV WT, single and double mutant strains.
The invention provides substituted benzoic acid containing compounds that are potent inhibitors of wild-type (WT) and double mutant strains of HIV-1 RT, particularly the double mutation K103N/Y181C.
In a first aspect of the invention, there is provided a compound of formula I: 
wherein
R2 is H, halogen, (C1-4)alkyl, O(C1-4)alkyl, NH(C1-4alkyl) or N(C1-4alkyl)2;
R4 is H or CH3;
R5 is H or CH3;
R12 is H, halogen, (C1-4)alkyl, CF3, or NO2;
R13 is H, (C1-4)alkyl, halogen, OH, or NH2, with the proviso that R12 and R13 are not both H; and
R14 is COOR14a wherein R14a is H or (C1-6)alkyl; or R14 is (C2-4)alkenylCOOR14a 
wherein R14a is as defined herein; or R14 is (C1-4)alkylCOOR14a wherein R14a is as defined herein;
or a salt or a prodrug thereof
According to a second aspect of the invention, there is provided a pharmaceutical composition for the treatment or prevention of HIV infection, comprising a compound of formula I, as described herein, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.
According to a third aspect of the invention, there is provided a method for the treatment or prevention of HIV infection, comprising administering to a patient an HIV inhibiting amount of a compound of formula I or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition, both as defined herein.
According to a fourth aspect of the invention, there is provided a method for treating or preventing HIV infection comprising administering a pharmaceutical composition comprising a compound of formula I, as described herein, in combination with an antiretroviral drug.
According to a fifth aspect of the invention, there is provided a method for preventing perinatal transmission of HIV-1 from mother to baby, comprising administering a compound of formula I or a pharmaceutical composition, as described herein, to the mother before giving birth.
The following definitions apply unless otherwise noted:
As used herein, the terms xe2x80x9c(C1-2)alkylxe2x80x9d, xe2x80x9c(C1-4)alkylxe2x80x9d and xe2x80x9c(C1-6)alkylxe2x80x9d, either alone or in combination with another radical, is intended to mean acyclic alkyl radicals containing up to two, four, or six carbon atoms respectively. Examples of such radicals include methyl, ethyl, propyl, butyl, 1-methylethyl, 1-methylpropyl, 2-methylpropyl, and 1,1-dimethylethyl.
As used herein, the term xe2x80x9c(C2-4)alkenylxe2x80x9d, either alone or in combination with another radical, is intended to mean an unsaturated, acyclic radical containing two to four carbon atoms.
As used herein, the term xe2x80x9chalogenxe2x80x9d means a halogen atom and includes fluorine, chlorine, bromine and iodine.
As used herein, the term xe2x80x9cpharmaceutically acceptable saltxe2x80x9d includes those derived from pharmaceutically acceptable bases and is non-toxic. Examples of suitable bases include choline, ethanolamine and ethylenediamine. Na+, K+, and Ca++ salts are also contemplated to be within the scope of the invention (also see Pharmaceutical salts, Birge, S. M. et al., J. Pharm. Sci., (1977), 66, 1-19, incorporated herein by reference).
As used herein, the term xe2x80x9cprodrugxe2x80x9d refers to pharmacologically acceptable derivatives, such that the resulting biotransformation product of the derivative is the active drug, as defined in compounds of formula I. Examples of such derivatives include, but are not limited to, esters and amides. (see Goodman and Gilman in The Pharmacological Basis of Therapeutics, 9th ed., McGraw-Hill, Int. Ed. 1995, xe2x80x9cBiotransformation of Drugs, p 11-16, incorporated herein by reference).
Preferably, R2 is H, halogen, (C1-4)alkyl, O(C1-4)alkyl or N(C1-4alkyl)2. Even preferably, R2 is H, Cl, F, (C1-4)alkyl, O(C1-4)alkyl, or N(C1-4alkyl)2. More preferably R2 is H, Cl, F, CH3, OMe, or OEt. Most preferably, R2 is H.
Preferably, R4 and R5 are not both the same.
More preferably, R4 is H.
More preferably, R5 is CH3.
Preferably, R12 is halogen, (C1-4)alkyl, CF3, or NO2. More preferably, R12 is Br, Cl, CH3 or CH3CH2. Most preferably, R12 is CH3 or CH3CH2.
Preferably, R13 is H, CH3, halogen, OH, or NH2. More preferably, R13 is H, CH3, or OH. Most preferably, R13 is H.
Preferably, R14 is COOH, COOMe, (C2-4)alkenylCOOH, or (C1-4)alkylCOOH. More preferably, R14 is COOH, CHxe2x95x90CHxe2x80x94COOH, CH2COOH, or CH2CH2COOH. Most preferably, R14 is COOH.
The compounds of formula I are effective inhibitors of wild type HIV as well as inhibiting the double mutant enzyme K103N/Y181C.
The compounds of formula I possess inhibitory activity against HIV-1 reverse transcriptase. When administered in suitable dosage forms, they are useful in the treatment of AIDS, ARC and related disorders associated with HIV-1 infection.
Another aspect of the invention, therefore, is a method for treating HIV-1 infection which comprises administering to a human being, infected by HIV-1, a therapeutically effective amount of a novel compound of formula I, as described above. Whether it be termed treatment or prophylaxis, the compound may also be used to prevent perinatal transmission of HIV-1 from mother to baby, by administration to the mother prior to giving birth.
The compounds of formula I may be administered in single or divided doses by the oral or parenteral routes. A suitable oral dosage for a compound of formula I would be in the range of about 0.5 mg to 3 g per day. A preferred oral dosage for a compound of formula I would be in the range of about 100 mg to 800 mg per day for a patient weighing 70 kg. In parenteral formulations, a suitable dosage unit may contain from 0.1 to 250 mg of said compound, preferably 1 mg to 200 mg. It should be understood, however, that the dosage administration from patient to patient will vary and the dosage for any particular patient will depend upon the clinician""s judgement, who will use as criteria for fixing a proper dosage the size and condition of the patient as well as the patient""s response to the drug.
When the compounds of the present invention are to be administered by the oral route, they may be administered as medicaments in the form of pharmaceutical preparations, which contain them in association with a compatible pharmaceutical carrier material. Such carrier material can be an inert organic or inorganic carrier material suitable for oral administration. Examples of such carrier materials are water, gelatin, talc, starch, magnesium stearate, gum arabic, vegetable oils, polyalkylene-glycols, petroleum jelly and the like.
The compounds of formula I can be used in combination with an antiretroviral drug known to one skilled in the art, as a combined preparation useful for simultaneous, separate or sequential administration for treating or preventing HIV infection in an individual. Examples of antiretroviral drugs that may be used in combination therapy with compounds of formula I, include but are not limited to, nucleoside/nucleotide reverse transcriptase inhibitors (such as AZT and Tenofovir), non-nucleoside reverse transcriptase inhibitors (such as Nevirapine), protease inhibitors (such as Ritanovir), viral fusion inhibitors (such as T-20), CCR5 antagonists (such as SCH-351125), CXCR4 antagonists (such as AMD-3100), integrase inhibitors (such as L-870,810), TAT inhibitors, other investigational drugs (such as PRO-542, BMS-806, MC-114 or AI-183), antifungal or antibacterial agents (such as fluconazole), and immunomodulating agents (such as Levamisole). Moreover, a compound of formula I can be used with another compound of formula I.
The pharmaceutical preparations can be prepared in a conventional manner and finished dosage forms can be solid dosage forms, for example, tablets, dragees, capsules, and the like, or liquid dosage forms, for example solutions, suspensions, emulsions and the like. The pharmaceutical preparations may be subjected to conventional pharmaceutical operations such as sterilization. Further, the pharmaceutical preparations may contain conventional adjuvants such as preservatives, stabilizers, emulsifiers, flavor-improvers, wetting agents, buffers, salts for varying the osmotic pressure and the like. Solid carrier material which can be used include, for example, starch, lactose, mannitol, methyl cellulose, microcrystalline cellulose, talc, silica, dibasic calcium phosphate, and high molecular weight polymers (such as polyethylene glycol).
For parenteral use, a compound of formula I can be administered in an aqueous or non-aqueous solution, suspension or emulsion in a pharmaceutically acceptable oil or a mixture of liquids, which may contain bacteriostatic agents, antioxidants, preservatives, buffers or other solutes to render the solution isotonic with the blood, thickening agents, suspending agents or other pharmaceutically acceptable additives. Additives of this type include, for example, tartrate, citrate and acetate buffers, ethanol, propylene glycol, polyethylene glycol, complex formers (such as EDTA), antioxidants (such as sodium bisulfite, sodium metabisulfite, and ascorbic acid), high molecular weight polymers (such as liquid polyethylene oxides) for viscosity regulation and polyethylene derivatives of sorbitol anhydrides. Preservatives may also be added if necessary, such as benzoic acid, methyl or propyl paraben, benzalkonium chloride and other quaternary ammonium compound.
The compounds of this invention may also be administered as solutions for nasal application and may contain in addition to the compounds of this invention suitable buffers, tonicity adjusters, microbial preservatives, antioxidants and viscosity-increasing agents in an aqueous vehicle. Examples of agents used to increase viscosity are polyvinyl alcohol, cellulose derivatives, polyvinylpyrrolidone, polysorbates or glycerin. Microbial preservatives added may include benzalkonium chloride, thimerosal, chloro-butanol or phenylethyl alcohol.
Additionally, the compounds provided by the invention can be administered by suppository.
The compound of the invention may be made using the skills of a synthetic organic chemist. Exemplary reaction schemes are shown in Schemes 1 to 4 below. Substituents R2, R4, R5, R12, R13, R13, and R14 are as defined herein, 
Briefly, aromatic substitution (SNAR) of 1(i) with Etxe2x80x94NH2 produces intermediate 1(ii). Thereafter, halogenation of the 5-position using a brominating agent (for example, NBS or bromine) gives 1(iii). Ring closure of 1(iii) via a base-mediated SnAR reaction forms the tricyclic intermediate 1(iv). Introduction of the R2 substituent proceeds via an aromatic substitution of the C-2 chlorine in 1(iv) thereby giving compound of intermediate 1(v). 
The sequence of scheme 2 is analogous to one described by J. M. Klunder et al.; J. Med. Chem. 1998, 41, 2960-71, and C. L. Cywin et al.; J. Med. Chem. 1998, 41, 2972-84. Briefly, aromatic substitution (SNAR) of 2(i) with Etxe2x80x94NH2 produces intermediate 2(ii). Reduction of the nitro group (for example using catalytic hydrogenation) produces 2(iii). A base mediated condensation reaction of 2(iii) with, for example, 5-bromo-2-chloro-3-pyridinecarbonyl chloride, provides 2(iv). Ring closure of 2(iv) proceeds via a base-mediated SnAR reaction to form the tricyclic intermediate 2(v). The R5 methyl group in 2(vi) may be introduced by art recognized alkylation using, for example, methyl iodide. 
Briefly, a base-mediated condensation reaction between 3(i) and 3(ii) gives intermediate 3(iii). Aromatic substitution (SNAR) of 3(iii) with Etxe2x80x94NH2 produces intermediate 3(iv). Ring closure of 3(iv) proceeds via a base-mediated SnAR reaction to form a tricyclic intermediate, which is alkylated to give compound of intermediate 3(v). 
Briefly, a base-mediated condensation reaction between 4(i) and 3(ii) gives intermediate 4(ii). Aromatic substitution (SNAR) of 4(ii) with Etxe2x80x94NH2 produces intermediate 4(iii). Ring closure of 4(iii) proceeds via a base-mediated SnAR reaction to form a tricyclic compound of intermediate 1(v). 
Briefly, cross-coupling of bromo derivative 5(i), synthesized as described herein, with an allyl tin reagent in an aprotic solvent (e.g. DMF) and in the presence of a catalyst, forms C-8 substituents 5(ii). Oxidation of the double bond (e.g. by ozonolysis to produce an ozonide), followed by a reduction, produces the C-8 hydroxyethyl substituent 5(iii). Using a Mitsunobu-type reaction, naphthyl derivatives 5(iv), 5(v) or 5(vi) when Y is R14 with the exception of COOH, are condensed with 5(iii) to produce compound of formula I. Alternatively, when Y is a R14 group precursor, for example COOCH3, a Mitsunobu-type reaction can be used to condense 5(iv) or 5(v) with 5(iii), and thereafter Y can be chemically converted into R14 substituents, for example by saponification of COOCH3 to give COOH, thereby giving compound of formula I.
As stated before, the compound provided by the invention inhibit the enzymatic activity of HIV-1 RT. Based upon testing of these compound, as described below, it is known that they inhibit the RNA-dependent DNA polymerase activity of HIV-1 RT. It is known (data not shown) that they also inhibit the DNA-dependent DNA polymerase activity of HIV-1 RT. Utilizing the Reverse Transcriptase (RT) Assay described below, compound can be tested for their ability to inhibit the RNA-dependent DNA polymerase activity of HIV-1 RT. Certain specific compound described in the Examples which appear below, were so tested. The results of this testing appear in Table 1 as IC50 and EC50.